\documentclass{standalone}
\usepackage{tikz}
\usepackage{ctex,siunitx}
\setCJKmainfont{Noto Serif CJK SC}
\usepackage{tkz-euclide}
\usepackage{amsmath}
\usepackage{wasysym}
\usetikzlibrary{patterns, calc}
\usetikzlibrary {decorations.pathmorphing, decorations.pathreplacing, decorations.shapes,}
\begin{document}
\small
\begin{tikzpicture}[>=latex,yscale=2]
  % \useasboundingbox(0.9,0)rectangle(5.1,5);
  \draw[<->] (0,1.5)node [right]{$e$}--(0,0)--(7,0)node[right]{$t$};
  \draw [dashed](0,-1)--(2*3.1416,-1);
  \draw [dashed](0,1)--(2*3.1416,1);
  \foreach \x in {1,2,...,6}
  {
      \draw [dashed](\x*3.1416/3, -1)--(\x*3.1416/3, 1);
  }
  \draw [ultra thick] plot[domain=0:2*3.1416, samples=1000] function{sin(x)} ;
  \draw (0,0)--(0,-1.5);
  \draw [ultra thick] plot[domain=0:2*3.1416, samples=1000] function{sin(x-3.1416*2/3)} ;
  \draw [ultra thick] plot[domain=0:2*3.1416, samples=1000] function{sin(x+3.1416*2/3)} ;
  \draw(3.1416*2/3,-1)--(3.1416*2/3,-1.5);
  \draw [<->] (0,-1.3)--node[fill=white]{$\dfrac{T}{3}$}(3.1416*2/3,-1.3);
  \node at (3.1416/2,1.2){$e_A$};
  \node at (3.1416/2+3.1416*2/3,1.2){$e_B$};
  \node at (3.1416/2+3.1416*4/3,1.2){$e_C$};
\end{tikzpicture}
\end{document}